Hydraulic power-transmission system



Aug. 26, 1941- H. SINCLAIR EI'AL I HYDRAULIC POW ER -TRAN SMISSION SYSTEM Filed Dec. 23, 1938 Patented Aug. 26, 1941 HYDRAULIC POWER-TRANSMISSION SYSTEM Harold Sinclair, Kensington, London, and Robert Grimsey Cooper, Isleworth, England, assignors to Hydraulic Coupling Patents Limited, London, England, a company of Great Britain Application December 23, 1938, Serial No. 247,414

In Great Britain December 24, 1937 1 Claim.

This invention relates to power-transmission systems of the kind in which a driving machine is coupled to a driven machine, which is required to run at various speeds relative to the ratio of the two machines.

and 66%.

Where it is required to drive at various speeds a driven machine which imposes a load fluctuating independently of the speed, for example a mechanical stoker, or a conveyer, or a kiln, the use of a coupling having the Vulcan form of working circuit, while enabling the speed of the speed of the driving machine, by a hydraulic 5 coupling of the kinetic type which is provided driven machine to be adjusted by varying the with means whereby, when the system is operdegree of filling of the circuit, allows substantial ating, the liquid content of the working circuit and objectionable fluctuations to occur in its of the coupling can be varied so as to alter the speed in consequence of, and in general in inslip in the coupling and consequently the speed verse relation to, the above-mentioned fluctuations in the load.

The hydraulic couplings in present general use Where a coupling having an interrupted core in such systems have the Vulcanform of working guide ring is used to drive such a fluctuating circuit with a continuous core guide ring around load, the resultant fluctuations in speed are much which the vortex circulation takes place; and larger and more objectionable than those occurthe torque-slip characteristic curves of such ring when the Vulcan coupling with a continuous couplings, plotted with torque as abscissa for core guide ring is used. various degrees of filling with constant impeller An object of the present invention is to provide speed, radiate from the origin and (with the a. power-transmission system 'of the kind set exception of those where the liquid content is forth, in which'such speed fluctuations are reat or near its normal maximum value, when the duced and which is especially adapted for a characteristic curve is nearly horizontal and the driven machine imposing a load which varies slip at normal torque is of the order of 3%) have indeterminately. 1n general a slope which increases with reduction This invention resides in the discovery that in filling and increase in torque at torque values the coupling characteristics can be widely inexceeding the normal torque as above defined. fiuenced by varying the cross section of the core Thus, as the torque increases above the normal guide ring and that the object of the invention torque, under any constant degree of partial 1111- can be attained by suitably thickening this ring ing of the working circuit, a constant increment in a radial direction so that it extends nearer to to the torque causes in general an increasing the inner profile diameter of the working circuit. increment to the -slip, although the slopes of the According to this invention, therefore, in a curves vary considerably over'the working range power-transmission system of the kind hereinbetween slip values of .20 and 66% and torque before set'forth, wherein the driven machine imvalues from 80% of'normal torque upwards. ppsesa load fluctuating independently of the Recently hydraulic couplings have come into speed, and wherein the hydraulic coupling has use, in particular for driving centrifugal pumps vaned impeller and runner elements together and fans, which in general impose a load varying forming a toroidal working circuit containing a according to a fixed law with the speed at which core guide ring aroundwhich the vortex circuthey are driven in which both parts of thecore lation is adapted to take place, the cross-secguide ring are interrupted, as described in Patent 40 tional area of the return junction betweensaid No.. 2,139,107 of- N. L. Alison issued December 6, elements is 'lessthan the cross-sectional area of 1938, with the object of obviating a flat-spot Y the flow junction between said elements and the effect in the quantity-slip characteristic curve of cross-sectional area of the circuit passages varies the'usual Vulcan coupling hereinabove referred smoothly between said junctions, the arrangeto. Thecoupling with such an interrupted core ment being such that the torque-slip characterguide ring, which is particularly suitable forsuch istic curves for .various degrees of filling of the drives, has torque-slip characteristic: curves coupling, over a useful part of the ranges of which have a considerably steeper slope in the torque and slip, are rendered flatter with referregion between 80% and normal torque for parence to the torque axis than the curves of tial degrees of filling between slip values of 20 couplings now in use.

For example, one interrupted core The invention will be further described by way coupling tested gave a torque-slip curvefor 62% of example with reference tothe' accompanying filling the slope of which to the torque axis was diagrammaticdra'wing, in which: very steep up to twice the normal torque. Fig, 1 is an elevation of the driving mechanism of a chain-grate stoker for a steam boiler, and

Fig. 2 is a sectional elevation of the hydraulic coupling shown in Fig. 1.

Referring to Fig. 1, the stoker grate I is driven through gearing contained in a casing H by an alternating-current electric motor [2 having its shaft l2a coupled to the driving shaft I3 of the gearing by a hydraulic coupling I l.

This coupling (Fig. 2) includes an impeller element 15 fixed by a flanged shaft coupling I6 to the shaft lZa of the motor 12', and a runner element l1 fixed to a driven shaft l8 which in turn is fixed to the driving shaft l3 of the gearing. The impeller and runner elements are juxtaposed to form a toroidal working circuit of oval section and are provided respectively with radial vanes l9 and 20 and with core guide members 2| and 22 which are juxtaposed to form a ring. This ring extends nearer to the couplin axis than is customary, and is so shaped that the radial width of the flow junction 23 between operates in such a way that all its torque-slip characteristic curves, within at least the range o! filling exceeding 50%, have a slope to the horizontal torque axis which, within the range of torque values between normal and twice normal torque and slip values not exceeding 66%, is less .flow junction (J) 7.5 and the radial width of the elements l5 and I1 is equal to theradial width of the return junction 24, these junctions being disposed in a common plane. Thus the cross-sectional area of the impeller passages increases smoothly from its inlet at 24 to its outlet at- 23, and the cross-sectional area of the runner passages decreases smoothly from its inlet at 23 to its outlet at 24.

Control means for obtaining any desired degree of filling of the working circuit include an eccentrically mounted scoop tube 25 housed in a rotatable reservoir chamber 26 and capable of being rocked by a control lever 21 so as to displace the scooping mouth in part radially and thereby cause it to transfer more or less liquid from the reservoir chamber 26 to the working circuit whence liquid returns to the reservoir through restricted drain ports 3|. This arrangement for varying the degree of filling of the working circuit is fully described .in the patent of H. Sinclair and A. C. Basebe, No. 2,187,667, issued Jan. 16, 1940. The control lever 21 may be coupled by a link 28 (Fig. 1) to an actuating member 29 of a telemotor 30 of a boiler control system.

The working circuit of the coupling shown in Fig. 2 is proportioned as follows, the outer profile diameter (D) of the working circuit being taken as 100%:

Per cent. of D Inner profile diameter (d) 31 Radial width of flow junction (J) '7 Radial width of return junction (7) 7 Maximum width of circuit (W) taken axially of the coupling 30 A hydraulic coupling having radial vanes andan oval section working circuit in general similar to that shown in Fig. 2 and proportioned within the following limits:

' posed between the core ring and the boundary,

the return junction (9') 6, the ratio of return area to flow area will be 31%. It the outer pr file diameter (D) be 100, the inner profile diameter (d) 40; the radial width of flow junction (0"), 6 and the radial width of return junction (7') 7.5, the ratio of return area. to flow area will be 63%.

The working circuit may be provided with guide rings of roughly semi-circular section disas indicated by dotted lines 32 in Fig. 2.

The improved power-transmission system can therefore be operated over a substantially wider range of torque values than the known systems without involving such wide fluctuations in speed of the driven machine as do the .known systems due to fluctuations in the load imposed by the driven machine when the hydraulic coupling is kept partly filled with a constant quantity of liquid. Nevertheless the speed of the driven machine can be readily varied in known manner by altering the degree of filling.

We claim:

A power transmission system of the kind in which a driving machine s coupled to a driven machine, which is required to run at various speeds relative to that of the.driving machine and which imposes a load fluctuating independently of the speed. by a hydraulic coupling of the kinetic type which is provided with impeller and runner elements having substantially radial vanes and together forming a working circuit which has substantially the section of an oval disposed with its major axis radial and of which the inner profile diameter is between 30 and 40 per cent. of the outer profile diameter, said circuit containing annular core guide means around which the vortex circulation is adapted to take place, and the flow and return jlmctions of said circuit being disposed substantially in a common plane and having each a radial width of between 6 and 7.5 per cent. of said outer profile diameter, and means whereby, when the system is operating, the liquid content of said working circuit can be varied so as to alter the slip in the coupling and consequently the speed ratio of the two machines.

HAROLD SINCLAIR. ROBERTGRHISEY COOPER; 

